What should I do if there is a blemish on the leaves of the tomato? How to prevent it?
Why is there a blemish on the leaves of tomato? Experienced growers know that this is a leaf mold in tomato. Once this disease occurs, it must be treated promptly, otherwise it will be finished until it becomes grayish purple.
Tomato leaf mold is a fungal disease caused by the genus Bacillus subtilis, commonly known as "black disease", which can damage multiple parts, but mainly leaves. At the beginning of the onset of the leaf, oval or irregular spots appear on the front, and the back is grayish white. The gray-purple or dark-brown velvet mold layer will appear on the front and back of the lesion, but it is common on the back of the lesion. When the condition is serious, the leaves may be dry or even reduced. Tomato leaf mold fungus like warm and high humidity, temperature 20 ° C -25 ° C, relative humidity of more than 90% is conducive to disease occurrence and aggravation. The peak of the disease is likely to occur in the season from cold to warm or from warm to cool; the growth period of easy onset is the fruit setting period.
Tomato leaf mold, which mainly harms leaves, and also harms stems, flowers and fruits in severe cases. It is also one of the major diseases commonly found in tomatoes. So how to prevent it properly?
Causes of tomato leaf mold
The pathogen of leaf mold likes high temperature and high humidity environment. The most suitable climatic conditions for the disease are temperature 20~25°C and relative humidity above 95%. The susceptible period of tomato is the flowering result period. Fields with continuous cropping, poor drainage, poor ventilation, too closed in the field, and high air humidity have a serious onset. In the early spring of the year, the temperature is low and rainy, continuous rainy or rainy and rainy. In the autumn and autumn, the temperature is high and the rainy years are heavy.
The path of leaf mold transmission is airflow. After the completion of the propagation, the infection began, and the pores invaded from the back of the leaves of the tomato. The hyphae spreaded between the cells, and the water and nutrients of the plants were absorbed to form lesions.
Tomato leaf mold prevention and treatment method
Because of the complexity of the causes of leaf mold, breeding for disease resistance is difficult. Therefore, before seeding, the seeds are recommended to be exposed to sunlight for 2-3 days, then soaked in warm water at 55 °C for 15-20 minutes, and continuously stirred, and then dried for sowing.
1 timely pruning: after the onset, before the application of the drug, we pruned the pruning, removed the diseased leaves and took them away from the planting, and then concentrated destruction. It can reduce the source of the disease, but also can be ventilated and transmitted.
2 temperature and humidity regulation: Because the pathogen of leaf mold likes high temperature, high humidity weather, it is very necessary to adjust the temperature and humidity. Humidity should be controlled at a relatively low level.
3 reasonable fertilizer: increase the application of phosphate fertilizer, potassium fertilizer. Watering should not be flooded with large water to avoid excessive moisture content. Ventilate in time after watering to avoid stagnation for a long time.
4 drug control: use 47% spring Lei Wang copper, an acre of 50-55 grams of water with 90-120 kg spray.
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